What causes tornadoes?

Tornadoes happen when warm, humid air gets trapped beneath a layer of cool, dry air, and winds at ground level move in a different direction than those above. This can cause the rising air to spin like a top, creating a funnel cloud.

Where are tornadoes most likely to occur?

Tornadoes are particularly common in the central U.S., where warm air from the Gulf meets cold air from the Arctic. Although the worst tornadoes tend to happen in the region known as “Tornado Alley” (which extends from the Rockies to the Appalachians and from central Texas to the Canadian prairies), there are many other tornado-prone areas in the U.S. (notably the Mississippi Valley and the lower Tennessee Valley). Peak tornado season is generally springtime, though the frequency tends to shift from south to north in the late spring to midsummer.

What’s the difference between a watch and a warning?

A tornado watch means there are weather conditions in your area that could produce a tornado — you should keep an eye out for updates and be prepared to act. A tornado warning means a tornado has been sighted or the Doppler radar indicates a tornado is imminent. You should seek shelter immediately.

What are the signs of a tornado?

A funnel cloud is the most obvious sign, but not all tornadoes have funnels, so look for whirling debris or dust under a bank of thick clouds. If you hear a load roar (similar to a train) that doesn’t fade after a few seconds, head for cover. Heavy rain or hail followed by an abrupt wind shift or sudden stillness can also indicate a tornado — be aware that precipitation or low clouds can hide the funnel from view. More information is available from FEMA here.

What should I do in the event of a tornado?

Form a plan and designate a meeting spot ahead of time. If you are under a tornado warning or notice any signs of a tornado approaching, head for a basement or other underground shelter and get under something sturdy, like a work bench. If that’s not possible, take cover in an interior stairwell, hallway, bathroom or closet on the lowest floor. Do not open the windows (the belief that this will equalize pressure is a myth). Keep away from windows, glass, and shelves where items might fall on you, and cover yourself with a mattress, sleeping bag, or other thick padding.

If you’re outdoors, take shelter in a sturdy building. If you can’t, lie facedown on low ground and cover your head with your hands. Stay away from trees and cars, which could be blown onto you.

What if I’m driving?

A vehicle is not a safe place to be in a tornado — the force of the twister can lift up even a heavy vehicle and toss it. If the tornado is distant but visible and traffic is light, you can try to get out of its path by driving away at a right angle to the funnel. Then, as soon as you can, seek shelter underground (if possible) or in a sturdy building.

If flying debris strikes your vehicle while you’re driving, quickly pull over and park. If you can safely get to an area that’s lower than the road, such as a ditch, leave your car and lie facedown in that spot, protecting your head with your hands. Otherwise, remain in the car with your seat belt on, drop your head below window level, and try to cover yourself with some type of cushion such as a blanket or coat. Do not take shelter under bridges or overpasses — the winds can send debris under the structure or even force your car out and into the storm.

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about Ellen

Ellen has spent many years as a professional wordsmith, helping to shed light on such topics as world travel, cargo pants, and the porosity of bath tiles. As a freelance copywriter for Esurance, she brings her boundless curiosity to the world of insurance. Outside work, she can be found cheering on the San Francisco Giants, hiking in the Oakland hills, and (barely) resisting smuggling penguins home from Antarctica.